ARS | Publication request: LARGE DROPLET, AIR-ASSIST AND COPPER APPLICATION EVALUATIONS

Submitted to: Ohio Fruit and Vegetable Growers Congress
Publication Type: Proceedings
Publication Acceptance Date: February 10, 2000
Publication Date: N/A

Technical Abstract: Current disease management programs provide growers with little information regarding recommended application techniques. While small droplets provide good coverage, they often lack sufficient energy to deposit deep into a canopy. Unless there is sufficient air turbulence, small, slow moving droplets also have a tendency to follow air streams around leaves or canopies. Air-assisted delivery can provide the extra energy necessary to drive spray material into a canopy and increase chances of deposition on the target area. Placing an electrical charge on spray droplets may also increase deposition efficiency. Large droplet applications can avoid some of the deposition and drift problems associated with small droplets but may not provide sufficient spray coverage. A series of field experiments was conducted to evaluate the affect of various application parameters on spray deposition and disease management. Imaging technology and colorimetry techniques were used to quantify deposit quality and quantity. An air inclusion, low-drift nozzle did produce relatively high deposits compared to other hydraulic nozzles but the air inclusion technology did not appear to improve spray coverage. Only air-assisted delivery was able to provide significant underside leaf coverage. However, the traditional nozzle type used to make fungicide applications, a high pressure, hollow cone nozzle, did produce good upper surface leaf coverage. Adding copper ions to the spray solution, at levels recommended for sanitation purposes, did not significantly improve sprayer performance. Continuing experiments serve to illustrate where various application methods are best suited to make the most efficient delivery of pest management materials.